With development and evolution of wireless networks, more and more services are provided, which requires additional frequency spectrum resources to support massive data transmission. On the basis of using the existing long term evolution (LTE) network, cellular radio network operators have begun to make researches on how to use unlicensed frequency spectrum resources, such as a 5 GHz ISM (Industrial Scientific Medical) frequency band. Meanwhile, WiFi wireless industry is deploying more and more WiFi systems on unlicensed frequency bands. Since communication systems of different operators have equal rights to use the unlicensed frequency bands, it is urgent in the industry to solve the problem of how to use the same unlicensed frequency band fairly and effectively. At present, the industry generally reaches an agreement that an unlicensed frequency band should be used with the assistance of a licensed frequency band and provides services to terminals by means of carrier aggregation.
In an LTE system, user equipment (UE) reports a power headroom to a base station (eNB) through a Media Access Control (MAC) layer. The power headroom indicates a difference between a maximum transmission power of the user equipment and an estimated uplink transmission power of the user equipment and is an important basis for the base station to perform uplink scheduling and power control. Various communication systems in the LAA system have equal rights to use resources on the unlicensed frequency band, that is, a channel on the unlicensed frequency band is not always idle, and the LAA system generally has a problem of hidden nodes, which results in great interference, thus a problem to be solved in this disclosure is to effectively ensure the power headroom report of the user equipment in the LAA system.